Sprinting is one of the most versatile forms of exercise, as it can be utilized to build power and speed, increase muscle size, shred body fat, and increase your cardiovascular capacity and muscular endurance. No other single exercise can effectively address all of those qualities. Learning how to modulate the intensity, duration, and rest intervals will allow you to target the appropriate energy systems and muscle fiber types for the training effect you are after. Learning how to appropriately fit them in with your strength training routine will ensure that the workouts complement each other.
If you are a speed and strength junkie who is looking to squeeze every ounce of performance out of your body, some form of sprints should be a staple in your training program. If you have been weight training for years with steady progress but you feel like your training has been stagnant and your results could be better, adding sprints into your routine will help you see results faster.
Sprints blast the fast-twitch muscles of the posterior chain (calves, hamstrings, glutes, and spinal erectors). The abdominals, obliques, shoulder flexors, and extensors are also heavily involved. Sprinting also trains the stretch-shortening cycle (a quick eccentric contraction followed by powerful concentric contraction), which carries over to improved jumping ability and other explosive plyometric exercises.

Sprint Variations

It's best to run sprints outside on a field or track rather than on a treadmill. On a treadmill, there is a reaching motion during the running stride because the running surface is moved underneath your feet, which limits hamstring involvement and overworks the hip flexors. Additionally, it is harder to match the treadmill to your true sprinting speed. An exception to this would be the non-motorized, self-powered treadmills such as the ones made by Woodway, but those are a second-best option. The running mechanics are still not the same as sprinting on the ground, and there is no wind resistance. If you are after speed, power, or muscle mass gains, stick to real sprints. If you simply want to build up your lung capacity and increase your caloric burn, a treadmill will work just fine.
Hill sprints are another variation that shift the emphasis of the movement because of the steeper angle of the hill. They can be used in any of the programs we will discuss below, just be aware that if you want to prioritize building top speed, it would be better to spend more time sprinting on flat ground. Stair sprints are also another great exercise, but the mechanics of that movement are different than hill sprints. Still, they are great for building up your lung capacity and muscular endurance.
Finally, sled pushing sprints, bicycle/stationary bike sprints, and prowler sprints are great conditioning exercises, but they are more quad dominant and don’t involve the stretch-shortening cycle to the degree of flat-ground sprints. This limits their carryover to explosive lower-body movements, making them less ideal if you are after speed and power gains or increased muscle mass in the posterior chain. Again, however, for general endurance purposes and fat loss, they are great options.
man sprinter
Want big, powerful, defined legs? Sprinters have them. [Photo courtesy Vicky Good]

3 Goal-Oriented Sprint Workout Formats

Sprinting for Speed and Power

When training for speed and power, focus on keeping the quality of training high and limiting the accumulation of fatigue during your workout. This means you will be sprinting relatively short distances and taking longer rest periods between sets. The longer rest periods are necessary to allow your body to replenish its phosphocreatine stores, which are depleted after about 10 seconds of high intensity effort, and for your fast-twitch muscle fibers and central nervous system (CNS) to recover. A work-to-rest ratio of 1:15-1:20 is appropriate for this type of sprint, meaning that if you do a 10 second all-out sprint, resting for 150-200 seconds would be appropriate. If you are used to running sprints as a conditioning exercise to enhance lung capacity and muscular endurance, this will seem like a long time, but to make improvements to power and speed, it is important to work at close to 100% capacity. Save the interval sprints that get your legs burning for another day.
There are two ways you can incorporate these types of sprints into your current strength training routine: perform them first in your workout followed by power or maximal strength training for the lower body, or perform the sprints in a separate training session on the same day that you do a strength/power workout in the gym. If you separate the sessions, which one you do first depends on what you want to prioritize. If you need to work on speed and acceleration, then perform the sprints first. If you have deficits in strength, then do the strength training first.
If it’s your first time combining the workouts and it’s been a while since you’ve sprinted, cut back on the number of sets for both the sprints and the strength training. It will take a few workouts to build up to 100% effort sprints in order for the connective tissue to adapt to the stress of sprinting.
Speed and Power Session
Morning workout:

A. 12x10m sprint, 45 sec rest

B. 6x50m sprint, 2 min rest

Evening workout:
A. Clean pulls 6x4
B. Back squat 5x3-5
C1. Glute ham raise 4x4-6
C2. Hanging leg raises 4x8-10

Sprinting for Leg Size

Sprinting is arguably the best exercise for building the hamstrings, glutes, calves, and quads. The primary difference between sprinting for increased muscle size and sprinting purely for speed and power is that a greater variety in training protocols can be used in hypertrophy training. If leg size is your main concern, then full ATP-PC and CNS recovery is not as critical, because performance gains are not the priority.
You still want to target the fast-twitch muscle fibers as they have a greater potential to gain in size. But a shift toward the endurance side of the spectrum will have a greater training effect on the Type IIa fast twitch muscle fibers, which have higher endurance potential than the Type IIb fibers. It is an oversimplification to say that there are only two types of fast twitch muscle fibers, but the important concept to remember is that short and intense sprints recruit more fast twitch muscle fibers and are more demanding on the CNS. Longer, lower-intensity runs have a minimal effect on fast twitch muscle fibers and are less demanding on the CNS. 
Keep the majority of the sprints in the 10-30 second range with a work-to-rest ratio of about 1:5-1:10 for the purposes of hypertrophy. Also include some sprint sessions where full recovery between sets is utilized, as discussed in the previous section on building speed and power. Following this with a moderately heavy bodybuilding-type session in the gym is a highly effective way of stimulating muscle growth in the legs.
Hypertrophy Session
Morning workout:
A. 10x50m sprint, 1 min rest between sets
B. 2x200m sprint, 2 min rest between sets
Evening workout:
A. Clean grip deadlift 10,10,8,8,6,6
B1. Dumbbell lunge 4x10-12
B2. Single leg lying leg curl 4x6-10
C1. Leg press 4x12-15
C2. Kneeling leg curl 4x8-10

Sprinting for Fat Loss and VO2 max

Sprinting in high intensity interval training (HIIT) format is the most commonly utilized type when paired with a traditional gym-based strength training routine. Also known as wind sprints, tempo runs, shuttle runs, or “suicides”, these types of sprints cause a large metabolic response resulting in increased calorie expenditure and an increase in the circulating levels of hGH and testosterone.1,2 These effects have a huge positive influence on reducing body fat.
The shortened rest periods for these sprints do not allow for full recovery, so the body has to rely on heavily on the anaerobic glycolysis energy pathway in order to produce ATP. This energy pathway results in temporary acidosis due to an accumulation of hydrogen ions, and it is theorized that this is what triggers the increase in hGH.3 On the other hand, these workouts are not as taxing on the CNS because the average sprint intensity is lower. 
The protocols for fat loss are similar to those for hypertrophy, with the main differences being that the rest intervals are shortened and the work periods are lengthened. For these sprints, the intensity of effort is more important than the actual velocity. Remember that the more you “feel the burn”, the greater the subsequent increase in hGH will be, so use that as motivation when you are wanting to call it quits before you have completed all of your reps. I like using a variety of sprint durations in the 10-60 second range and keeping the work-to-rest ratio between 2:1-1:3.
These fat loss workouts should be fairly short, under the 20-minute range including warm-up time, so they can be easily added onto the end of a gym workout or they can be performed as a separate workout on their own. Tacking on a short HIIT session at the end of your workout 2-4 times per week would be an effective addition to your routine that wouldn’t compromise your gains in the weight room. Do not perform these sprints immediately before a gym workout because you might be fairly wiped out after, making the strength training work you do following the sprints less effective.
Fat Loss and Endurance Session
A1. Back squat 4x12-15
A2. Lying leg curl 4x10-12
B1. Dumbbell split squats 3x15 each leg
B2. Horizontal back extensions 3x10-12
C. 6x100m sprint, 30 sec rest between sprints, 2 min rest after 6th set
D. 2x400m sprint, 2 min rest

Make the Program Your Own

Now you have a good idea of how to incorporate sprints into your training routine. If it has been years since you last sprinted, ease into these workouts and don't go 100 percent right away. Starting out at half of the suggested volume of work is a good place to start, and you can build your way up over the course of 2-3 weeks. Use the sample programs as guides and feel free to be creative and substitute exercises based on your individual needs and availability of equipment. If you want to see more sample combined sprint and weight training programs, including tips on how to effectively warm up for sprints, follow the link in my bio section below.
Need some more tips on getting started with sprints?
1. Hackney, A. C., K. P. Hosick, A. Myer, D. A. Rubin, and C. L. Battaglini. "Testosterone Responses to Intensive Interval versus Steady-state Endurance Exercise." Journal of Endocrinological Investigation J Endocrinol Invest 35, no. 11 (2012): 947-50. doi:10.1007/bf03346740. 
2. Wahl, Patrick, Christoph Zinner, Silvia Achtzehn, Wilhelm Bloch, and Joachim Mester. "Effect of High- and Low-intensity Exercise and Metabolic Acidosis on Levels of GH, IGF-I, IGFBP-3 and Cortisol." Growth Hormone & IGF Research 20, no. 5 (2010): 380-85. doi:10.1016/j.ghir.2010.08.001. 
3. Gordon, S. E., W. J. Kraemer, J. M. Lynch, and N. H. Vos. "Effect Of High-Intensity Cycle Exercise And Acid-Base Balance On The Proportion Of Free And Total Insulin-Like Growth Factor-1 In Human Serum." Medicine & Science in Sports & Exercise 25, no. Supplement (1993). doi:10.1249/00005768-199305001-00438. 
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